They can. -- If there are useful comments, you should consider them when preparing the MO version of your question, and give appropriate credit to the authors of the comments.

@SergeiAkbarov: You cannot (and should not) delete answered questions. What I meant is that you can delete a question which just got forgotten on Math.SE, and then post it here.

I think simultaneous cross-posts should rather be avoided than supported and encouraged. That said, if you have posted a question to Math.SE, and there is no answer for a considerable time and for a couple of consecutive days almost nobody looks at your question (check the view count), then you can delete the question on Math.SE and post it on MO, with a notice that it has previously been asked on Math.SE without success.

I think the idea behind your feature request makes sense, but implementing it in the suggested form would come along with the risk that a small group of people extends the scope of the site in a way with which the vast majority of the community does not agree. What one could do though is to increase the number of required votes in each close/reopen cycle.

@ToddTrimble: I think it should be uncontroversial that mathematicians support their colleagues who are persecuted by an authoritarian state.

@Dilaton: There is also a petition for Kıvanç Ersoy on change.org where it is more obvious how to sign (and a considerable number of colleagues have already done so).

Your question has not been closed as "off-topic", but as "unclear what you're asking". -- This means that in order to get your question reopened, you need to make clear what precisely you would like to know. Typical questions may have the form "Is it true that ...?", "Where can I find a proof of ... ?", etc. -- but rather not something not very clear like "I can't find closely related resources. Any help with that is appreciated.". Also, if a question is closed as "unclear" this often indicates that it is too long and / or hard to digest for a reader.

Is it at all obvious for a new user that by editing their question they always bump it to the top and thus cause inconveniences for other people if they do it often?

@René: At the time of writing this, Richard Stanley's question has score +28. -- I am not convinced that this is in line with your assertion that "the rules are clearly violated" by his question, at least not unless you elaborate on why you think they would. Site rules are not set in stone, but always up to interpretation by the community.

@René: At least in my understanding, like in 'real life' also on MO there is a notable difference between a person of some standing who acts under their real name and an anonymous 'user498487'.

The discussed question may be not great, but I wonder what should make it less on-topic than e.g. the question on where to buy premium white chalk which remained open for 5 years. In any case, I don't see a particular point in closing occasional borderline questions of people like Richard Stanley who have contributed a lot to this site -- if some people like them, why not just leave them open.

I think you should feel free to add the clarification to the question. -- As to "penalties for being argumentative", I don't think there is anything you need to worry about -- penalties for people who would like to be helpful would be strange. Also, as far as I see, you made valuable contributions to the site since its beginnings.

As to the "significant additional visibility" a question gets from a bounty, my impression is rather that the number of additional views a question gets after someone has placed a bounty on it is just about that the question would get after merely editing it -- though it would would be interesting to have this statement either confirmed or refuted by statistical data.